WHO Acknowledges Possible MERS Sustained Transmission

The recent mild and asymptomatic cases raise concerns about the possibility of large numbers of milder cases going undetected. While it is clear that human-to-human transmission does occur, it is not clear whether transmission is sustained in the community. The currently observed pattern of disease occurrence could be consistent either with ongoing transmission in an animal reservoir with sporadic spillover into humans resulting in non-sustained clusters, or unrecognized sustained transmission among humans with occasional severe cases.

The above comments from the latest WHO MERS-CoV update acknowledge that the MERS-CoV may be currently transmitting in a sustained manner.

As noted, prior results, including the confirmed or suspect mild and asymptomatic cases clearly demonstrated the possibility that the “seemingly sporadic” cases were in fact examples of sustained transmission, which was not easily recognized because of countries gaming the surveillance system, as well as as a focus on hospitalized cases, which represented the most severe cases. Thus, MERS transmisison may be similar to SARS transmission in 2003.

The above acknowledgement, which follows the confirmation of asymptomatic cases, helps explain the WHO decision to form an emergency committee which is meeting today and Thursday.